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Ironite is a supplemental fertilizer that contains nitrogen, potash, and minerals. It contains ingredients that will promote quick greening of lawn grasses, as well as slow-release ingredients for long-lasting green color. According to the label, Ironite will not burn lawns, but several of its ingredients can burn grass if not used properly.

Why Fertilizers Burn Lawns

Some types of fertilizers, especially water-soluble types, are nutrient salts. When added to the soil, they create a high concentration of salt that pulls the water out of the grass. This results in dry, brown grass that appears burned or scorched. The chance of fertilizer burn increases when the temperatures are high or the humidity is low. Decrease the chance of fertilizer burn by applying the recommended amount of fertilizer and watering immediately afterwards. If a large amount of fertilizer is spilled on the lawn, immediately scrape up the excess and thoroughly water in the remaining fertilizer to avoid burning the grass.

Nitrogen Overdose Can Burn

Ironite contains urea nitrogen, which dissolves rapidly when wet and has a high possibility of burning grass. When applied according to the directions, Ironite provides 0.1 pound of nitrogen per 1,000 square feet. The recommended rate to reduce the chance of fertilizer burn with any soluble nitrogen is 1 pound per 1,000 square feet. To exceed the recommended rate, a gardener would have to apply more than 100 pounds of Ironite to a 1,000 square foot area.

Other Nutrients That Burn

Muriate of potash is another soluble ingredient in Ironite that can burn lawns, although it is highly unlikely for the home gardener to do so. Since the recommended rate to prevent burning is 1½ pounds of 60 percent potash per 1,000 square feet, a gardener would need to apply more than 60,000 pounds of Ironite to a 1,000 square foot area. Ironite provides iron in the form of ferrous sulfate, which can burn grass if it is applied when the lawn is wet or the temperature is above 80 degrees. Watering it in immediately usually prevents burning. Too much boron can be toxic to grass and can burn the edges of the blades of grass, in addition to causing it to discolor and grow poorly. Even ½ to 1 ounce of boron per 1,000 square feet can cause soils that are high in boron to become toxic, so a gardener always should have the soil tested before using Ironite.

How to Use Ironite

Spread granular Ironite at the rate of 1 pound per 100 square feet of established lawn and thoroughly water it in immediately afterwards. Ironite should be used four times a year as a supplement to regular fertilization, and should not be applied more than 10 times a year. Wear long pants, long sleeves, and gloves when spreading Ironite, and thoroughly wash any exposed skin afterwards. Ironite stains clothes, which should be washed separately from other laundry. Do not allow people or pets on the lawn until it is completely dry. Ironite contains mercury, which is a toxic substance. Animals that ingest Ironite or contaminated items may become sick. Avoid getting Ironite or runoff in ditches, drains or bodies of water. Ironite stains rocks, flagstones, pavers, concrete, and wood hardscaping, so it should be swept off, not washed off with water.

About the Author

Melody Lee holds a degree in landscape design, is a Florida Master Gardener, and has more than 30 years of gardening experience. She currently works as a writer and copy editor. Her previous jobs include reporter, photographer and editor for a weekly newspaper.